The substructure of a deck must be
resistant to rot and is particularly
prone to moisture damage from below and from above. Ground level decks
often lack airflow from below if they are sealed around the outer
perimeter and from above when debris from overhead trees gets stuck in
cracks. This can create a situation where there are soft spots on the
deck boards and screws are coming loose due to not getting a bite into
the rotten joists.

We build rot proof structures by using stained pressure treated lumber,
allowing proper gapping on deck boards, and designing for proper
airflow around outer edge. If it is an existing deck we can also do a
restorative process whereby we prep the underside for a solid stain
application that protects and beautifies the structure.

Under coating is recommended on decks with decks or patios below them
or if they are visible from below. Generally this is more of an
aesthetic question since properly built upper level decks will be
fairly rot resistant even without staining. Ventilation and drainage
are the key factors. Also, with upper level decks we can
replace/install new joists if rot in certain areas does occur.